Short answer: for typical staff use, no. If teachers use AI for lesson planning, resource creation and letter drafting — with no pupil personal data involved — there is nothing to consent to, because no child's data is being processed.
When consent questions do arise
The picture changes if a school introduces a tool that processes pupil data (an AI marking platform, for example) or gives pupils direct access to an AI system. Those situations engage UK GDPR properly: a Data Protection Impact Assessment, a lawful basis, and transparent communication with parents — which may or may not involve consent depending on the basis your DPO identifies. See our guides to AI and GDPR and the AI procurement checklist.
What good practice looks like anyway
Even where consent isn't required, telling parents proactively how your school uses AI builds trust and pre-empts worry. A short letter and a page on the school website is usually enough — our guide to talking to parents about AI includes what to say.